1. Field of the Invention
Disclosed are a system and a method for establishing an absolute reference point for a cycle of a cyclically operating apparatus. More specifically, a system and method are provided for establishing an absolute reference point for a cycle of an envelope inserter in which periodic reciprocating motion of a rotating member-linked structural component of the inserter is utilized in the generation of the absolute reference point.
2. Description of the Background Art
An envelope inserter functions to place various inserts like billing statements, advertisements, coupons, return envelopes, and the like within a sending or mailing envelope. Traditionally, a shaft encoder is employed in association with a motor, a drive shaft, a timing shaft, or other rotating component on the envelope inserter to determine rotational positions for the rotating member associated with the encoder and thus, positional references for rotating member-linked components and processes during an envelope insertion cycle such as when to open a mailing envelope, when to pick an insert, when to fill a mailing envelope, when to wet and seal a mailing envelope, and the like. For precise positional references, a system and method are needed to calibrate or correlate a home position that indicates where the shaft encoder signals the zero reference point (ideally the starting position of an insert cycle) and an actual physical location on the motor shaft, drive shaft, timing shaft, or other rotating member. If the actual physical location on the rotating member for a particular process differs from where the encoder indicates the rotating member is located then the various processing steps may become disorganized and interrupt or jam the machine.
In the past, the standard home position or zero reference point calibration process entailed a technician manually aligning the timing shaft or other rotating member to a proscribed standard physical location and physically rotating the encoder zero position to correspond to that location, which resulted in about a .+-.5-10% reproducibility error. The correct encoder zero position was determined either by a visual and not very reproducible observation or it was determined, more precisely, by noting where a LED coupled into a control unit which received the encoder signal would light each time the home position was reached.
A difficulty with the traditional manual approach to determining the home position or zero reference point was that the physical alignment of the timing shaft or other rotating member often differed from one technician to another technician. A first technician might physically align one particular component of the inserter as zero and a second technician might select a different component to align or align the same component in a slightly different fashion, thereby introducing small, but significant inconsistencies in the process. The subject invention overcomes the irreproducibility inherent in the traditional zero reference point determining process by utilizing an index pulse that gives an "absolute" positional value that is not subject to the vagaries of individual alignment techniques. Preferably, the index pulse issues from the controller when the reciprocating component reaches the inner limit.
The foregoing information reflects the state of the art of which the applicant is aware and is tendered with the view toward discharging applicant's acknowledged duty of candor in disclosing information which may be pertinent in the examination of this application. It is respectfully submitted, however, that this information does not teach or render obvious applicant's claimed invention.